This invention relates to an improved accumulator type fuel injection nozzle and valve and valve actuator for such a nozzle.
A well known and popular type of fuel injection nozzle is the so-called accumulator type. With this type of fuel injection nozzle there is provided a housing that defines an accumulator chamber that is charged with fuel under pressure. The flow controlling injection valve of the nozzle has an actuator portion that is mounted within a small control chamber that is also pressurized with fuel under pressure. When it is desired to inject fuel, the pressure in the control chamber is rapidly reduced by opening a relief valve for that chamber and the pressure in the accumulator chamber opens the injector valve and permits the fuel to be discharged.
With this type of device, the actuator normally is formed integrally with the injector valve and is slidably supported within a bore that defines the control chamber. Obviously, it is desirable to provide a large diameter for the actuator portion of the injection valve so as to insure relatively high pressures acting on the injector valve from the control pressure chamber to hold the valve in its closed position. Normally, conventional systems require relatively heavy springs for holding the injector valve in its closed position and this has a number of disadvantages.
However, when a large diameter actuator portion is provided, it is difficult to assemble the complete mechanism. The reason for this is that the controlling portion of the injection nozzle is relatively small in size and when all of the parts are assembled, the clearances associated with large diameter actuator portions makes it difficult to insure smooth valve operation at a reasonable cost.
It is, therefore, a principal object of this invention to provide an improved actuator arrangement for the valve of an accumulator type fuel injection nozzle.
It is a further object of this invention to provide an improved supporting arrangement for the actuator portion of the injector valve that permits large diameters to be utilized while at the same time minimizing assembly problems and cost.